Field of the Invention
The invention relates particularly to a gate for slide valve, particularly for interrupting the flow of thick, viscid, finely, divided, or granular materials in conveying pipes, said valve comprised of a guide groove in the valve housing, for guiding the sliding plate, which guide groove is bounded laterally, in the valve internal flow passage having circular cross section, by pairs of guide strips which extend into flow passage.
When the sliding plate is in its open position, material of the medium being conveyed can settle in the guide groove. When the plate is then closed particularly if this closing occurs only at long time intervals, these deposits depending on their nature and amount can lead to frictional resistance which makes closing difficult; and to rapid wearing away of the guided edge of the plate. Accordingly, the lateral edge parts of the usually circular closing edge of the sliding plate, which edge in cross section usually has a recessed lower i.e. downstream region, are generally unable to expel any and all material which is deposited in the relatively long guide groove, by scraping the deposits from the wall of the groove. In addition there is a hazard that material thus scraped free, instead of moving into the main valve opening i.e., the flow passage, will be pushed into the lower i.e., closure guide groove bottom, in FIG. 2 which joins the lateral guide grooves, thereby making if difficult or impossible to completely move the sliding plate into closed position.
Accordingly, it has been proposed to provide the guide strips with a plurality of notches in relatively close succession, in the region of valve flow passage. When the sliding plate is in its open position, practically no material can deposit from the medium which flows through these notches. And when the sliding plate is in the process of being closed, any small amount of material deposited in the relatively short groove segments between notches can be pushed by the closing-edge of the sliding plate up to the next notch, where the material can then be washed away by the remainder of the flow.
Apart from the fact that the presence of the notches makes the valve housing more difficult to manufacture, the relatively narrow notches have the disadvantage that when the sliding plate is open they cause major disturbances to the flow in the flow passage, which flow is otherwise relatively smooth. These disturbances are detectable upon visual inspection. They result from the projection into the cylindrical flow passage of the guide strips bearing a plurality of generally sharp-edged notches, which projections have the effect of a set of gear teeth.